Field-pole magnets are arranged in a rotor core of a permanent magnet-embedded rotary electric machine. One conventionally-known example is a field-pole magnet formed by fracturing a magnet having a rectangular shape in a plan view (hereinafter simply referred to as a magnet) into a plurality of magnet pieces and bonding the plurality of magnet pieces with one another. By thus forming a field-pole magnet from a plurality of magnet pieces, the volume of each magnet piece is reduced, and overcurrent caused by a fluctuation in an active magnetic field is reduced. In this way, heating of the field-pole magnet associated with overcurrent is suppressed, and irreversible thermal demagnetization is prevented (see JP 2009-142081A).
According to JP 2009-142081A, cutouts are formed in advance on a plurality of intended fracture surfaces of a magnet, and the magnet is arranged between a punch with a convex multi-angular surface and a die with a concave multi-angular surface. By pushing the punch against the die, the magnet is fractured along the intended fracture surfaces. As a result, a plurality of magnet pieces are generated.